1. Field of the Invention
The invention relates to a transparent cover for a vehicle roof whose transparency can be controlled by applying voltage.
2. Description of Related Art
Such a vehicle roof is known, for example, from German Patent No. DE 36 14 547 C2. In this known device, the surface of a transparent glass cover has a bottom electrode, an inorganically reducing, color-forming layer, an electrolytic layer with a spacer containing electrolytic solution, an organically oxidizing, color-forming layer, a top electrode and a transparent cover glass laminated or applied on it. This multilayer pane forms the cover of a sun roof and the light incidence in the vehicle interior can be controlled by selectively changing the voltage on the electrodes. For aerodynamic reasons, vehicle roofs are generally made arched outward. Consequently, the transparent area must also be arched. The drawback in the known vehicle roof is that the multilayer cover must be made with the electrochromic area arched, which requires great expense, on the one hand, and, on the other hand, leads to a strong tendency to interference during further processing. Glass breakage leads to a large amount of waste, which makes the costs rise so much that series production was prevented up to now.
Similar vehicle roofs are known from published German Patent Application Nos. DE 36 43 690 C2 and DE 196 30 813 A1, and Published European Patent Application No. EP 0 436 283 A2.